Customs keep "popping" out of seal!

I've had my customs for awhile now and for some reason one side keeps on "popping" out of the seal. Its like when i push the custom in there will be a compression of air in my ear ( i think its called a seal right?) Then when i move my head it just "pops" out of seal .

Now I've got 2 questions

1. Does this mean i require a refit ?
2. Does this 'popping sound' actually damage the drivers?

Do you have any oil excess on your ears? I find my seals to break easily if I get too much oil. Once I washed them, it's damn tight. Hope this helps. As for question no. 2, I don't really get what you mean by 'popping sound'.